Humans are one of the species who laugh. Laughter is a sense of feeling good, happy and joyful. It is a response to humour, comprising two parts, gestures and production of sound. A hearty laugh triggers changes in the various parts of the body like arm, leg and trunk muscles. Fifteen facial muscles contract when […]
The lacrimal system is responsible for producing and secreting tears. It is situated near the eyeball. A person sheds three types of tears that are basal tears that keep the cornea nourished and lubricated; reflex tears, which help to wash out any irritant in the eyes from foreign particles like onions, and psychic or crying
Deafness is the complete inability to hear sound. It can occur at any age. A person may go deaf all of a sudden due to an accident or a severe viral infection, or gradually over time as a result of disease, nerve damage or injury caused by noise. Ear infection, fluid build-up behind the eardrum,
Colour-blindness is colour vision deficiency that is an inability or reduced ability to differentiate between colours. It is a condition in which a person is unable to perceive colour differences under normal light. Ishihara test is done using different number plates to find if the person is colour-blind. This condition arises due to a fault
Fever is a physical condition in which the temperature of the body increases higher than normal. A normal temperature can vary from person to person, but it is usually around 98.6 F. Fever can result from viral, bacterial or parasitic infections like common cold, urinary tract infection, malaria, etc. or have a non-infectious cause such
Pain is an unpleasant feeling caused by illness or injury. It indicates discomfort in some part of the body and disappears when the painful stimulus is removed or as the body heals. Pain can also result due to an injury or a surgery. It hampers the daily routine of a person considerably. It can be
Warts are skin infections on the top layer of the skin. They are caused by the viruses of the ‘human papillomavirus’ (HPV) family. They occur when the outer layer of skin gets infected by this virus through a tiny scratch or cut. Then a rapid growth of cells on the outer layer of skin occurs
Muscles are the bundles of soft tissues in the bodies of animals. They are joined with bones and nerves. They help produce movement and keep the body parts in position. There are three types of muscles: skeletal muscles, smooth muscles and cardiac muscles. They constitute the major body mass of an organism. Skeletal muscles help
Freckles are cells containing colour present in the skin in small batches. They are flat, small and light brown in colour. People with a fair complexion, especially kids, are likely to get freckles. They appear when skin produces more melanin. Melanin is a pigment produced by skin cells to protect the skin from damage by
Bones are hard tissues that form the skeleton in humans and other vertebrates. A bone provides a structure to an organism. Bones protect and support organs and systems, store minerals, and give mobility. In humans, at birth there are more than 270 bones. However, as development takes place some bones fuse together resulting in finally
The brain is an organ that is the centre of the nervous system. It is located in the skull at the top of the spinal cord. It has three main parts: the cerebellum, the cerebrum and brainstem. The cerebrum is the biggest part of the brain. The brain is the decision-maker in the body. It
Blood is a red fluid which circulates in the body of humans and other vertebrates. It carries oxygen and nutrients to cells. It also carries carbon dioxide and impurities away from cells. Heart pumps blood throughout the body in specialised vessels called arteries and veins. Blood is mainly composed of red blood cells (RBCs), white
The cell was discovered by Robert Hooke in 1665. It is the smallest living structural and functional unit. It is a microscopic body, not visible to naked eyes. A human body is composed of trillions of cells. Bacteria can be single-celled. They are of different shapes and sizes, some of them are circular, some rectangular
Cats are the members of a special family which includes tigers, lions and leopards. Cats and the other members of the family are alike in many ways. Their bodies are adapted to hunt and kill. They owe their hunting expertise to their eyes, which are adapted to see in the dark. Their eyes open wide
The word ‘amphibian’ is a Greek word that means ‘double life’. Most amphibians live both on land and in water. They begin their life in water with gills and tails. As they grow, they develop lungs and legs for their life on land. The skin of amphibians has no hair or fur. Instead, their skin